The invention relates to a device for the stepped displacement of work pieces, especially within a press, comprising at least one or two gripper rail(s), which can be displaced back and forth in the feed direction for the feed and return motion, which have gripper parts or gripper zones for engaging the work pieces, and which then can be moved back into the original position for engaging the work pieces and for moving in the feed direction, wherein at least two levers that can pivot parallel or mirror-symmetric to each other in the plane of motion, in a plane parallel to this plane of motion, or in a plane at an angle to this plane of motion are attached to the gripper rail(s), and for a device with two parallel gripper rails, these levers of one of the gripper rails can pivot in the opposite sense to those of the other gripper rail.
Such a device with two parallel gripper rails is known from DE 102 06 773 C1, with additional state of the art concerning such gripper rails being cited in this publication. This device has proven advantageous, primarily in presses, in which the gripper rails are arranged between the press stands overlapping in their longitudinal direction and in the feed direction of the work pieces. Here, it is favorable that only the gripper rails and the work pieces grasped by these rails, as well as possible grippers or gripper parts on the gripper rails, that is, relatively small masses, must be moved.
Presses are also known, however, in which the spacings of the press stands are too small to allow the gripper rails to project through these stands. In such presses, the gripper rails must be arranged within the intermediate spaces of the press stands and also must be moved back and forth, so that only a limited space is also available for the drive for these movements of the gripper rails.
Indeed, presses with such gripper rails are already known, in which the movements of the gripper rails run transverse to their longitudinal extent within the spacing of the press stands, but these presses require drives, which are arranged outside of the press outline and therefore special protective measures for the operator and also safety spacings are necessary due to the movements running outside of the press outline. Here, linear drives are known, which are arranged transverse to the feed motion and to the longitudinal extent of the rails, which project out of the press outline perpendicular to the gripper rails, and which require not only the mentioned safety spacings, but also make the accessibility and the ability to monitor the running of the gripping and feed motions more difficult, because a user must be positioned at a correspondingly large distance to the gripper rails.